diff options
Diffstat (limited to 'lib/Transforms/InstCombine')
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 7c67bf6..79c5d88 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1289,13 +1289,21 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, } case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) - case Instruction::AShr: - // Only handle equality comparisons of shift-by-constant. - if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) - if (Instruction *Res = FoldICmpShrCst(ICI, cast<BinaryOperator>(LHSI), - ShAmt)) + case Instruction::AShr: { + // Handle equality comparisons of shift-by-constant. + BinaryOperator *BO = cast<BinaryOperator>(LHSI); + if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { + if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt)) return Res; + } + + // Handle exact shr's. + if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) { + if (RHSV.isMinValue()) + return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS); + } break; + } case Instruction::SDiv: case Instruction::UDiv: |